Clarification please on O2 sensors and STFT.
- delcowizzid
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Re: Clarification please on O2 sensors and STFT.
The swinging also fills the catalytic convertor with excess o2 each swing lean so it can do its job burning off the bad stuff
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
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Re: Clarification please on O2 sensors and STFT.
Ok, thank you, but if the STFT is showing negatives, is that reducing (leaning) fuel amounts put in to the engine or increasing fuel (richer) ?
i just want to get this stuff clear in my head so i can remember it.![Smile :)](./images/smilies/icon_e_smile.gif)
i just want to get this stuff clear in my head so i can remember it.
![Smile :)](./images/smilies/icon_e_smile.gif)
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Re: Clarification please on O2 sensors and STFT.
negative numbers means it's pulling fuel out.. It's leaning it out from what it's calculated for fuel delivery.. You'll always see them doing something..JohnDee68 wrote:Ok, thank you, but if the STFT is showing negatives, is that reducing (leaning) fuel amounts put in to the engine or increasing fuel (richer) ?
i just want to get this stuff clear in my head so i can remember it.
As far as a stock vehicle If the long term are + or - 10 then I leave it alone. They don't set codes til they get on the high side of 25 plus or minus.
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Re: Clarification please on O2 sensors and STFT.
just to clarify, as terminology in different industries can reflect different outcomes. When you say "pulling fuel out", do you mean reducing fuel into the combustion chamber or "pulling fuel out" of the injector resulting in more fuel in the combustion chamber?
- delcowizzid
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Re: Clarification please on O2 sensors and STFT.
Reducing the amount of fuel injected
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
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Re: Clarification please on O2 sensors and STFT.
![thumbup :thumbup:](./images/smilies/icon_thumbup.gif)
I now understand more and have come to the conclusion as follows.
O2 sensor reading Lower than 500mv = LEAN Condition
O2 sensor reading Higher than 500mv = RICH Condition
STFT & LTFT POSITIVE = ADDING FUEL
STFT & LTFT NEGATIVE = REDUCING FUEL
![thumbup :thumbup:](./images/smilies/icon_thumbup.gif)
![thumbup :thumbup:](./images/smilies/icon_thumbup.gif)
- delcowizzid
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Re: Clarification please on O2 sensors and STFT.
Only when cruising is that correct. full throttle will be in the mid 0.800 to 0.900 range
If Its Got Gas Or Ass Count Me In.if it cant be fixed with a hammer you have an electrical problem
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Re: Clarification please on O2 sensors and STFT.
Ok, I will note that. But for me I don't go WOT. I am more a cruise driver.delcowizzid wrote:Only when cruising is that correct. full throttle will be in the mid 0.800 to 0.900 range
![Smile :)](./images/smilies/icon_e_smile.gif)
- hsv08
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Re: Clarification please on O2 sensors and STFT.
I always work off LL = "Low is Lean" Meaning Lower then 500 millivolts.
Depending on how the LT's and ST's are setup in the tune will define there behaviors, ( im sure some of the XDFs allow you to define how many percent your ST's can be before changing the LT's)
But this is why you would normally use the math LTFT + STFT, Your STFT will always move about within a couple percent when fueling is close.
I try to insure that my trims are within a couple percent but always try to stay on the -2-3% mark. Its always better to be a bit richer then leaner.
trims minus = Removing fuel from base VE or MAF based on O2 swings
trims positive = Adding fuel from base VE or MAF based on O2 swings
Depending on how the LT's and ST's are setup in the tune will define there behaviors, ( im sure some of the XDFs allow you to define how many percent your ST's can be before changing the LT's)
But this is why you would normally use the math LTFT + STFT, Your STFT will always move about within a couple percent when fueling is close.
I try to insure that my trims are within a couple percent but always try to stay on the -2-3% mark. Its always better to be a bit richer then leaner.
trims minus = Removing fuel from base VE or MAF based on O2 swings
trims positive = Adding fuel from base VE or MAF based on O2 swings
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Re: Clarification please on O2 sensors and STFT.
Thanks hsv08,
I like the "LL" method to recall it.
I think I struggle at the moment trying to learn tuning my car. So I'm taking one step at a time.
I like the "LL" method to recall it.
I think I struggle at the moment trying to learn tuning my car. So I'm taking one step at a time.